My trane xl 1200 is stuk in heat. Will not go into cool. It is like the reverse vale is bad. Can you help me

Check for power at the reversing valve while the unit is active in the a/c mode. If power is present and the valve does not switch to the cooling mode the valve is probably bad or the valve coil is defective. Time to call for Professional ON SITE service for a replacement and to check for proper operation of your equipment.